<?php
$n = trim(fgets(STDIN));
$weights = explode(" ", trim(fgets(STDIN)));
$sum = array_sum($weights);
if ($sum % 2) {
	echo 'impossible';
	exit;
}
$dp = array_fill(0, $sum + 1, false);
$dp[0] = true;
foreach ($weights as $w) {
	for ($i = $sum; $i >= 0; $i--) {
		if (!$dp[$i]) continue;
		$dp[$i + $w] = true;
	}
}
echo $dp[$sum / 2] ? "possible" : "impossible";
?>